The present invention is generally directed to track-type machines. More particularly, the present invention is directed to a machine frame assembly for a track-type machine.
Traditionally, track-type machines have been driven by a power source contained within the body of the track-type machine, as seen, for example, in U.S. Pat. No. 3,828,873. Usually, these power sources have been mechanically coupled to input shafts that extend through the machine frame and engage a pair of sprockets. These sprockets generally are supported on opposite sides of the machine frame and are rotatably mounted to the machine frame. The sprockets may directly or indirectly drive an endless track about a roller frame to provide movement of the machine. Each roller frame is generally supported behind its midpoint by a pivot shaft, which extends from the machine frame. Each roller frame is also generally supported in front of its midpoint by an equalizer bar attaching both roller frames together. The midpoint of the equalizer bar is attached at the lateral midpoint of the machine frame. The equalizer bar controls the rotation of each roller frame about its pivot shaft. As the front of one roller frame is forced to rise by externally applied forces or uneven ground, the opposite roller frame is forced to fall by the equalizer bar. Each roller frame has idler wheels affixed to each end to support the endless track as it rotates.
One limitation of having a sprocket that is mounted to the machine frame of the track-type machine is that the roller frame is constrained in its movement. Another limitation of having a sprocket that is statically mounted to the machine frame is that the sprocket is cantilever supported off the machine frame. This may allow the sprocket to deflect and cause the endless track to twist when contacting the sprocket.
One approach for providing power to drive a track-type machine is disclosed in U.S. Pat. No. 3,656,642. In this arrangement, a roller frame is rigidly fixed to a pair of hardbar members to form a solid frame. A rear drive sprocket is supported on the roller frame and driven by an engine connected to a multi-speed transmission. The transmission in turn is connected to the rear drive sprocket by a conventional clutch mechanism. This track-type machine has a similar limitation to that of U.S. Pat. No. 3,828,873 in that the roller frame cannot pivot independent of the machine frame.
The present invention solves one or more of the problems associated with existing track-type machine designs.
One aspect of the present invention is directed to a machine frame assembly for a track-type machine including a machine frame, a hollow pivot shaft attached to the machine frame and configured to support a drive assembly for a track-type machine to allow pivotal movement of the drive assembly relative to the machine frame, and a power source, a portion thereof extending into the hollow pivot shaft and a portion thereof mounted adjacent to an end of the hollow pivot shaft. The power source is configured to transmit power through the hollow pivot shaft.
In yet another aspect, the invention is directed to a track-type machine including a machine frame, a hollow pivot shaft attached to the machine frame, a power source, and a drive assembly supported on the hollow pivot shaft. The power source is configured to transmit power through the hollow pivot shaft. The drive assembly includes a drive system and an endless track that engages the drive system.
The present invention is also directed to a method of driving a track-type machine. The track-type machine includes a machine frame, a hollow pivot shaft attached to the machine frame, a power source configured to transmit power through the hollow pivot shaft, and at least one drive assembly supported on the hollow pivot shaft. The drive assembly includes a drive system and an endless track that engages the drive system. The method includes transmitting power from the power source through the hollow pivot shaft to the drive system. The drive system drives the endless track.